氦

例句：

1. 1. Helium is a noble gas that is used in rockets.
   氦是一种稀有气体，用于火箭。
2. 2.The helium balloon floated up to the ceiling.
   氦气球飘到了天花板上。
3. 3. Helium is lighter than air, which makes it ideal for use in spacecraft.
   氦比空气轻，这使得它非常适合用于太空飞船。